Hongfeng Lake,a key drinking-water source located in Karst areas,was selected to analyze the microorganisms associated with nitrogen cycle.Dilution plate method and most probable number method were used to determine t...Hongfeng Lake,a key drinking-water source located in Karst areas,was selected to analyze the microorganisms associated with nitrogen cycle.Dilution plate method and most probable number method were used to determine the distribution condition of ammonifier,ammonium-oxidizing bacteria,nitrite-oxidizing bacteria and denitrifier in surface sediment in eight sites.The results showed that the amount of ammonifier,ammonium-oxidizing bacteria,nitrite-oxidizing bacteria and denitrifier in eight sites were 104-106 CFU/g,105-107 MPN/g,105-108 MPN/g and 105-109 MPN/g,respectively.The sampling site with the largest amount of denitrifier was Daposhang,and the other sampling sites had no significant difference;the sampling site of Huyudong bridge had the largest amount of ammonium-oxidizing bacteria;the amount of nitrite-oxidizing bacteria in Xinzhuang was higher than that of other sampling sites;the sampling site of Daposhang had the larger amount of denitrifier.展开更多
Rapid nitrogen(N) transformations and losses occur in the rice rhizosphere through root uptake and microbial activities. However,the relationships between rice roots and rhizosphere microbes for N utilization are stil...Rapid nitrogen(N) transformations and losses occur in the rice rhizosphere through root uptake and microbial activities. However,the relationships between rice roots and rhizosphere microbes for N utilization are still unclear. We analyzed different N forms(NH+4,NO-3, and dissolved organic N), microbial biomass N and C, dissolved organic C, CH4 and N2O emissions, and abundance of microbial functional genes in both rhizosphere and bulk soils after 37-d rice growth in a greenhouse pot experiment. Results showed that the dissolved organic C was significantly higher in the rhizosphere soil than in the non-rhizosphere bulk soil, but microbial biomass C showed no significant difference. The concentrations of NH+4, dissolved organic N, and microbial biomass N in the rhizosphere soil were significantly lower than those of the bulk soil, whereas NO-3in the rhizosphere soil was comparable to that in the bulk soil. The CH4 and N2O fluxes from the rhizosphere soil were much higher than those from the bulk soil. Real-time polymerase chain reaction analysis showed that the abundance of seven selected genes, bacterial and archaeal 16 S rRNA genes, amoA genes of ammonia-oxidizing archaea and ammonia-oxidizing bacteria, nosZ gene, mcrA gene, and pmoA gene, was lower in the rhizosphere soil than in the bulk soil, which is contrary to the results of previous studies. The lower concentration of N in the rhizosphere soil indicated that the competition for N in the rhizosphere soil was very strong, thus having a negative effect on the numbers of microbes. We concluded that when N was limiting, the growth of rhizosphere microorganisms depended on their competitive abilities with rice roots for N.展开更多
The principal aim of this paper is to develop an approach to realize stable biological nitrogen removal via nitrite under normal conditions. Validation of the new method was established on laboratory-scale experiments...The principal aim of this paper is to develop an approach to realize stable biological nitrogen removal via nitrite under normal conditions. Validation of the new method was established on laboratory-scale experiments applying the sequencing batch reactor（SBR） activated sludge process to domestic wastewater with low C/N ratio. The addition of sodium chloride（NaCI） to influent was established to achieve nitrite build-up. The high nitrite accumulation, depending on the salinity in influent and the application duration of salt, was obtained in SBRs treating saline wastewater. The maintenance results indicated that the real-time SBRs can maintain stable nitrite accumulation, but conversion from shorter nitrification-denitrification to full nitrification-denitrification was observed after some operation cycles in the other SBR with fixed-time control. The presented method is valuable to offer a solution to realize and to maintain nitrogen removal via nitrite under normal conditions.展开更多
Microsensor measurements and fluorescence in situ hybridization （FISH） analysis were combined to investigate the microbial populations and activities in a laboratory-scale sequencing batch reactor （SBR） for comple...Microsensor measurements and fluorescence in situ hybridization （FISH） analysis were combined to investigate the microbial populations and activities in a laboratory-scale sequencing batch reactor （SBR） for completely autotrophic nitrogen removal over nitrite （CANON）. Fed with synthetic wastewater rich in ammo- nia, the SBR removed 82.54-5.4% ofinfluent nitrogen and a maximum nitrogen-removal rate of 0.52kgN.m 3.d-l was achieved. The FISH analysis revealed that aerobic ammonium-oxidizing bacteria （AerAOB） Nitrosomonas and anaerobic ammonium-oxidizing bacteria （AnAOB） dominated the community. To quantify the microbial activities inside the sludge aggregates, microprofiles were measured using pH, dissolved oxygen （DO）, NH＋, NO＋ and NO3 microelectrodes. In the outer layer of sludge aggregates （0-700 μm）, nitrite-oxidizing bacteria （NOB） showed high activity with 4.1 gmol-cm3＋ h-1 of maximum nitrate production rate under the condition of DO concentration higher than 3.3 mg. L 1. Maximum AerAOB activity was detected in the middle layer （depths around 1700 μm） where DO concentration was 1.1 μg. L-1. In the inner layer （2200-3500μm）, where DO concentration was below 0.9 mg. L-1, AnAOB activity was detected. We thus showed that information obtained from microscopic views can be helpful in optimizing the SBR performance.展开更多
基金Supported by Science and Technology Found Project of Guizhou Province(QKH J[2008]2239)~~
文摘Hongfeng Lake,a key drinking-water source located in Karst areas,was selected to analyze the microorganisms associated with nitrogen cycle.Dilution plate method and most probable number method were used to determine the distribution condition of ammonifier,ammonium-oxidizing bacteria,nitrite-oxidizing bacteria and denitrifier in surface sediment in eight sites.The results showed that the amount of ammonifier,ammonium-oxidizing bacteria,nitrite-oxidizing bacteria and denitrifier in eight sites were 104-106 CFU/g,105-107 MPN/g,105-108 MPN/g and 105-109 MPN/g,respectively.The sampling site with the largest amount of denitrifier was Daposhang,and the other sampling sites had no significant difference;the sampling site of Huyudong bridge had the largest amount of ammonium-oxidizing bacteria;the amount of nitrite-oxidizing bacteria in Xinzhuang was higher than that of other sampling sites;the sampling site of Daposhang had the larger amount of denitrifier.
基金Supported by the National Natural Science Foundation of China(No.41090280)
文摘Rapid nitrogen(N) transformations and losses occur in the rice rhizosphere through root uptake and microbial activities. However,the relationships between rice roots and rhizosphere microbes for N utilization are still unclear. We analyzed different N forms(NH+4,NO-3, and dissolved organic N), microbial biomass N and C, dissolved organic C, CH4 and N2O emissions, and abundance of microbial functional genes in both rhizosphere and bulk soils after 37-d rice growth in a greenhouse pot experiment. Results showed that the dissolved organic C was significantly higher in the rhizosphere soil than in the non-rhizosphere bulk soil, but microbial biomass C showed no significant difference. The concentrations of NH+4, dissolved organic N, and microbial biomass N in the rhizosphere soil were significantly lower than those of the bulk soil, whereas NO-3in the rhizosphere soil was comparable to that in the bulk soil. The CH4 and N2O fluxes from the rhizosphere soil were much higher than those from the bulk soil. Real-time polymerase chain reaction analysis showed that the abundance of seven selected genes, bacterial and archaeal 16 S rRNA genes, amoA genes of ammonia-oxidizing archaea and ammonia-oxidizing bacteria, nosZ gene, mcrA gene, and pmoA gene, was lower in the rhizosphere soil than in the bulk soil, which is contrary to the results of previous studies. The lower concentration of N in the rhizosphere soil indicated that the competition for N in the rhizosphere soil was very strong, thus having a negative effect on the numbers of microbes. We concluded that when N was limiting, the growth of rhizosphere microorganisms depended on their competitive abilities with rice roots for N.
基金The Hi_Tech Research and Development Program(863) of China(2004AA601020) the National Natural Science Foundation of China(No.50478047)andthe Open Grant of Beijing Key Laboratory
文摘The principal aim of this paper is to develop an approach to realize stable biological nitrogen removal via nitrite under normal conditions. Validation of the new method was established on laboratory-scale experiments applying the sequencing batch reactor（SBR） activated sludge process to domestic wastewater with low C/N ratio. The addition of sodium chloride（NaCI） to influent was established to achieve nitrite build-up. The high nitrite accumulation, depending on the salinity in influent and the application duration of salt, was obtained in SBRs treating saline wastewater. The maintenance results indicated that the real-time SBRs can maintain stable nitrite accumulation, but conversion from shorter nitrification-denitrification to full nitrification-denitrification was observed after some operation cycles in the other SBR with fixed-time control. The presented method is valuable to offer a solution to realize and to maintain nitrogen removal via nitrite under normal conditions.
基金This work was supported by the National Natural Science Foundation of China （Grant No. 51108367）, Specialized Research Fund for the Doctoral Program of Higher Education （No. 20116120120009）, Natural Science Foundation of Shaanxi Province （No. 2014JQ7243） and innovative research team of Xi＇an University of Architecture and Technology.
文摘Microsensor measurements and fluorescence in situ hybridization （FISH） analysis were combined to investigate the microbial populations and activities in a laboratory-scale sequencing batch reactor （SBR） for completely autotrophic nitrogen removal over nitrite （CANON）. Fed with synthetic wastewater rich in ammo- nia, the SBR removed 82.54-5.4% ofinfluent nitrogen and a maximum nitrogen-removal rate of 0.52kgN.m 3.d-l was achieved. The FISH analysis revealed that aerobic ammonium-oxidizing bacteria （AerAOB） Nitrosomonas and anaerobic ammonium-oxidizing bacteria （AnAOB） dominated the community. To quantify the microbial activities inside the sludge aggregates, microprofiles were measured using pH, dissolved oxygen （DO）, NH＋, NO＋ and NO3 microelectrodes. In the outer layer of sludge aggregates （0-700 μm）, nitrite-oxidizing bacteria （NOB） showed high activity with 4.1 gmol-cm3＋ h-1 of maximum nitrate production rate under the condition of DO concentration higher than 3.3 mg. L 1. Maximum AerAOB activity was detected in the middle layer （depths around 1700 μm） where DO concentration was 1.1 μg. L-1. In the inner layer （2200-3500μm）, where DO concentration was below 0.9 mg. L-1, AnAOB activity was detected. We thus showed that information obtained from microscopic views can be helpful in optimizing the SBR performance.
